Hi, NJ2Boardwalk!
Tough choice, and I'd have to answer "it depends." Is your party all adults? Small children? Where will you spend most of your time? More details would help others advise you to your individual situation.
I agree with the "location, location, location" arguement above, but for this very same reason, we always choose the POLY! We love the proximity to the MK and TTC; the monorail access is just awesome, and the buses have always been very efficient in our experience. We enjoy World Showcase also, but we don't find it too inconvenient to walk through FW to the Epcot Monorail and walk from TTC to our room.
We also much prefer the theme of the Poly. The Epcot resort area is really lovely, but we spend every summer weekend at the Jersey shore, so we look for something "different" when we're in WDW. Beach Club to us looks and feels like every beach house we're ever rented. Which is great, if you're looking for that kind of thing. The pool at the BC/YC is best on property, but we also adore the Volcano pool. The slide is great and the view and landscaping are, in our opinion, beyond compare at WDW. We all have different tastes. I HATE chocolate ice cream, but I try to keep an open mind and imagine that others are not totally crazy to like it!
Enjoy making your decision! Aloha.